1. Field of the Invention
Generally, the present invention relates to the fields of molecular biology and medicine. More specifically, the present invention is in the field of cancer research, especially ovarian cancer diagnosis.
2. Background of the Invention
In order for malignant cells to grow, spread or metastasize, they must have the capacity to invade local host tissue, dissociate or shed from the primary tumor, enter and survive in the bloodstream, implant by invasion into the surface of the target organ and establish an environment conducive for new colony growth (including the induction of angiogenic and growth factors). During this progression, natural tissue barriers such as basement membranes and connective tissue have to be degraded. These barriers include collagen, laminin, fibronectin, proteoglycans and extracellular matrix glycoproteins. Degradation of these natural barriers, both those surrounding the primary tumor and at the sites of metastatic invasion, is believed to be brought about by the action of a matrix of extracellular proteases.
Proteases have been classified into four families: serine proteases, metallo-proteases, aspartic proteases and cysteine proteases. Many proteases have been shown to be involved in human disease processes and these enzymes are targets for the development of inhibitors as new therapeutic agents. Certain individual proteases are induced and overexpressed in a diverse group of cancers, and as such, are potential candidates for markers of early diagnosis and targets for possible therapeutic intervention. A group of examples are shown in Table 1.
There is a good body of evidence supporting the downregulation or inhibition of individual proteases and the reduction in invasive capacity or malignancy. In work by Clark et al., inhibition of in vitro growth of human small cell lung cancer was demonstrated using a general serine protease inhibitor. More recently, Torres-Rosedo et al., [Proc. Natl. Acad. Sci. USA. 90, 7181-7185 (1993)] demonstrated an inhibition of hepatoma tumor cell growth using specific antisense inhibitors for the serine protease hepsin. Metastatic potential of melanoma cells has also been shown to be reduced in a mouse model using a synthetic inhibitor (batimastat) of metallo-proteases. Powell et al. [Cancer Research, 53, 417-422 (1993)] presented evidence to confirm that the expression of extracellular proteases in a non-metastatic prostate cancer cell line enhances their malignant progression. Specifically, enhanced metastasis was demonstrated after introducing and expressing the PUMP-i metallo-protease gene. There is also a body of data to support the notion that expression of cell surface proteases on relatively non-metastatic cell types increases the invasive potential of such cells.
To date, ovarian cancer remains the number one killer of women with gynecologic malignant hyperplasia. Approximately 75% of women diagnosed with such cancers are already at an advanced stage (III and IV) of the disease at their initial diagnosis. During the past 20 years, neither diagnosis nor five-year survival rates have greatly improved for these patients. This is substantially due to the high percentage of high-stage initial detection of the disease. Therefore, the challenge remains to develop new markers that improve early diagnosis and thereby reduce the percentage of high-stage initial diagnoses. The ability to disengage from one tissue and re-engage the surface of another tissue is what provides for the morbidity and mortality associated with this disease. Therefore, extracellular proteases may be good candidates for markers of malignant ovarian hyperplasia.
Thus, the prior art is deficient in a tumor marker useful as an indicator of early disease, particularly for ovarian cancers. The present invention fulfills this long-standing need and desire in the art.
This invention allows for the detection of cancer, especially ovarian cancer, by screening for stratum corneum chymotrytic enzyme (SCCE) mRNA in tissue. Stratum corneum chymotrytic enzyme specifically associates with the surface of 80 percent of ovarian and other tumors. Proteases are considered to be an integral part of tumor growth and metastasis, and therefore, markers indicative of their presence or absence are useful for the diagnosis of cancer. Furthermore, the present invention is useful for treatment (i.e., by inhibiting SCCE or expression of SCCE), for targeted therapy, for vaccination, etc.
In one embodiment of the present invention, there is provided a method for detecting malignant hyperplasia in a biological sample, comprising the steps of isolating mRNA from the sample and detecting stratum corneum chymotrytic enzyme mRNA in the sample. Typically, the presence of the stratum corneum chymotrytic enzyme mRNA in the sample is indicative of the presence of malignant hyperplasia, and the absence of the SCCE mRNA in the sample is indicative of the absence of malignant hyperplasia.
In another embodiment of the present invention, there are provided methods of inhibiting expression of stratum corneum chymotrytic enzyme in a cell by SCCE antisense mRNA or antibody specific for stratum corneum chymotrytic enzyme protein or a fragment thereof.
In yet another embodiment of the present invention, there is provided a method of targeted therapy to an individual, comprising the step of administering a compound to an individual, wherein the compound has a therapeutic moiety and a targeting moiety specific for stratum corneum chymotrytic enzyme.
In yet another embodiment of the present invention, there are provided methods of vaccinating an individual against SCCE or produce immune-activated cells directed toward SCCE by inoculating an individual with a SCCE protein or a fragment thereof that lacks SCCE protease activity.
In still another embodiment of the present invention, there are provided compositions comprising immunogenic SCCE fragment or an oligonucleotide having a sequence complementary to SEQ ID No. 30 (i.e., full length nucleotide sequence of SCCE, or fragments thereof as would be readily recognizable to one having ordinary skill in this art). Also embodied is a composition comprising the above-described oligonucleotide and a physiologically acceptable carrier. Additionally embodied is a method of treating a neoplastic state in an individual in need of such treatment, comprising the step of administering to the individual an effective dose of the above-described oligonucleotide.
In another embodiment of the present invention, there is provided a method of screening for compounds that inhibit stratum corneum chymotrytic enzyme activity, comprising the steps of contacting a sample with a compound, wherein the sample comprises SCCE protein; and assaying for SCCE protease activity. A decrease in the SCCE protease activity in the presence of the compound relative to SCCE protease activity in the absence of the compound is indicative of a compound that inhibits stratum corneum chymotrytic enzyme activity.
Other and further aspects, features, and advantages of the present invention will be apparent from the following description of the presently preferred embodiments of the invention. These embodiments are given for the purpose of disclosure.